This invention relates to methods of and apparatus for separating floating and suspended solids from a flowing liquid using continuous deflective separation, and particularly, but not solely to non-mechanical methods and apparatus.
More generally, the invention relates to apparatus and methods for separating solids or particulate matter from flowing liquids or gases. The invention has particular, although not exclusive, application to the filtration of floating and entrained solids from discharges of water. One particular application of the invention is in relation to storm water drain technology.
There are many applications where it is desirable to separate solids from a flowing liquid including:
1. Separation of solids from stormwater.
In many areas of the world, stormwater is directed to waterways and seas. Stormwater is a major carrier of solid pollutants such as plastics, cans, tree branches and animal feces, amongst other things to waterways and seas.
Endeavors have been made to limit the passage of at least some of these materials. One method used is by having grates across outlets from the drains but these have generally been unsatisfactory because the size of the grate must be such as to enable water to pass even if material is held against the grate by water pressure so it has been necessary that the grate be of substantial opening size. Also, even such grates can be blocked and it is essential to provide a flow path around or over the grate to prevent build up of water upstream in the drain system. A second alternative proposed has been the use of systems, such as cyclones and dynamic separators, to remove the waste. Whilst these can be efficient, they are too expensive to be used in the whole of a stormwater system.
2. Separation of liquid from sewage.
A major difficulty with many sewage plants is the sheer volume of liquid to be handled. This is aggravated where a “mixed” system, that is a system which carries both sewage and storm water is used. In many cases, sewage plants could handle more sewage if the quantity of liquid delivered therewith could be reduced, if, for example, liquid was removed from sewage before it enters trunk sewers. To date, this has not been considered feasible.
Also, there are regions where stormwater and sewage are received by the same system. This can cause difficulties where there are heavy rains which overload the system, as it is undesirable to permit raw sewage to pass to overflow.
3. Removal of pollutants from industrial wastes.
Many industrial plants must pay prohibitive rates to discharge polluted liquids into sewers. It would be most desirable to separate a part of the pollution before the waste is delivered to sewers and this would provide economies both to the plant and to the authority if this cost of the early removal of polluted matter was less than the cost, of cleaning up pollution later.